Review
of the 2007 Changes to 40 CFR 136
Tim Loftus
Earlier this year (2007) many changes to
the way we are required to preserve samples, what containers samples
can be stored in, and the holding times of these samples became
federal law. Additionally, many EPA test methods have been withdrawn
from the list of approved methods, while other ones have been added.
All samples collected, preserved, and analyzed for NPDES purposes must
adhere to these updated regulations for the reported results to be
valid.
The changes in federal law range from basic sampling procedures to
much more complex analytical analyses. All of these changes can be
found in the “Federal Register/ Vol. 72, No. 47/Monday, March 12,
2007/Rules and Regulations.”
A link to this document is:
http://www.access.gpo.gov/su_docs/fedreg/a070312c.html.
For the text of this, scroll to “Environmental Protection
Agency-Rules-Water Supply.” Eventually these will be available in book
form and will be part of the Code of Federal Regulations, Chapter 40,
part 136.
All these changes cannot be dealt with here; however, the following is
a review of some of the changes that affect most wastewater treatment
plant laboratories. Please note that while these requirements became
federal law last April, some regulatory agencies have different
interpretations on how and when they will be implemented. Always,
always, always check your NPDES regulatory agency as to how these
changes affect you.
Sample Preservation
For those samples which require cooling as part of the preservation
step, the new temperature requirement is now “less than or equal to 6
C.” You cannot round down the temperature to a single significant
digit to meet the temperature requirement. For example, a sample
temperature of 6.3 C cannot be rounded down to 6 C to meet the
preservation requirement. The previous preservation temperature was
“less than 4 C. The bacterial tests (fecal coliform, E. Coli,
Enterococci, etc.) preservation temperature remains the same at < 10
C.
Samples collected for metal analyses do not need to be preserved to a
pH of <2 with nitric acid until at least 24 hours prior to analyses.
The only exception is if the sample will be analyzed within 24 hours,
then acid preservation must be done immediately upon collection.
Most wastewater labs do not analyze for cyanide. However, many
treatment facilities must collect samples for cyanide analysis as part
of their Industrial Pretreatment Program. Sampling instructions are
quite extensive and cannot be covered here in its entirety. If cyanide
sampling is part of your sampling plan, check out the regulations in
the Federal Register so that you can meet the sampling requirement.
Holding Times
While most of the maximum holding times for all parameters have not
changed, the new regulations do specifically define exactly when the
holding time starts for a composite sample. “For a composite sample
collected with an automated sampler…the holding time begins at the
time of the end of collection of the composite sample.” (40 CFR 136,
Table II, note 4) For example, the 48-hour holding time for a
composite sample for BOD starts at the end of the composite period.
The holding time does not start with the first aliquot of a composite
sample. Previously, this has been a source of contention with some
regulatory agents.
Test Methods
Many test methods that were approved for NPDES reporting have now been
withdrawn. Most of these are EPA methods and a few are from Standard
Methods If your lab follows any of these withdrawn methods, then you
will have to find other approved methods for any NPDES required
analyses. Federal regulations list specific approved test methods from
EPA, Standard Methods (18th, 19th, and 20th editions) Standard Methods
on-line, ASTM, and USGS, as well as a few additional specific sources.
Changing a test method in your lab often requires more than just
listing the new method on top of a data sheet. While some analytical
methods from different sources are nearly identical to each other,
many are not. For example, EPA method 160.2 for Total Suspended Solids
- TSS (which is no longer an approved method) required using a
graduated cylinder to measure the sample volume. Standard Methods,
which is very different, requires the sample to be stirred on a
magnetic stirrer and the sample to be measured using a pipet. The USGS
method for TSS is similar to the EPA method and allows the use of a
graduated cylinder. So, if you were following EPA 160.2 for TSS
analysis, like most of us were, you need to choose another test
method. Whichever one you choose, you must follow it exactly.
There is also another aspect of changing test methods that often is
overlooked. Each source of test methods spells out what should be done
for quality control (QC) measures. Sometimes these can vary between
sources. If you follow the USGS method for TSS analyses, then you
should also be following the USGS recommendations for QC for that
method. For a procedure from Standard Methods, follow the Standard
Methods QC recommendations for that procedure.
The information in this article is very general. As usual, check your
federal, state, and local regulations. You may have additional
regulations or requirements that you must meet.
If you have any questions, suggestions, or comments, contact NEWEA Lab
Practices Committee Chair Tim Loftus at (508) 949-3865 timloftus@msn.com.
For more information on the NEWEA Laboratory Practices Committee,
please contact Tim Loftus or Elizabeth Cutone, NEWEA Executive
Director, 100 Tower Office Park, Woburn, MA 01801, (781) 939-0908,
ecutone@newea.org.
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